Canvas creates areas that cannot be drawn

phina.define('MainScene', {
    superClass: 'DisplayScene',
    init:function(){
        This.superInit (// Give Scene width, height too!)
            {
                width: 1024,
                height768
            }
        );

        for (varrow=0; row<32;row++){
            for(varcol=0;col<48;col++){
                varchipImage="ground";
                if(row%2==0&col%2==0){
                    chipImage="grassland"
                }
                this.bg=Sprite(chipImage).addChildTo(this);
                this.bg.setPosition(32*col,32*row);
                this.bg.origin.set(0,0);
            }
        }
    },
});

// main processing
phina.main(function(){
    var app = GameApp({
        startLabel: 'main',
        width: 1024,
        height —768,
        assets —ASSETS
    });

    app.enableStats();
    app.run();
});